It has heretofore been proposed to provide indwelling devices, such as catheters, with an inflatable cuff of flexible material at the distal end inside the body, the cuff being inflatable from outside the body by an elongated tubule leading along the catheter to a one way valve and syringe type pump outside the body.
It has also been proposed to interpose in the tubule near the proximal end, between the valve and the cuff, an inflatable pilot balloon so that inflation of the pilot balloon indicates inflation of the cuff within the body.
Such an inflation indicating bulb is disclosed in U.S. Pat. Nos.
2,883,986 to DeLuca et al Apr. 28, 1959 PA1 3,543,751 to Sheffer of Dec. 1, 1970 PA1 3,810,474 to Cross of May 14, 1974 PA1 3,989,571 to Hardutuneian of Nov. 2, 1976 PA1 4,178,939 to Stephens of Dec. 18, 1979.
In addition to merely indicating inflation or deflation of the cuff by corresponding inflation or deflation of an exterior pilot balloon, there are patents which disclose means on the pilot balloon for indicating the amount of pressure of inflation.
In U.S. Pat. No. 3,407,817 to Galleher, Jr. of Oct. 29, 1968 a tubular coil unwinds as pressure on a finger bulb pump is exerted, the greater the unwinding the greater the pressure in the cuff.
U.S. Pat. No. 4,016,885 to Bruner of Apr. 12, 1977 discloses an inflatable cuff type catheter with a pressure indicating means in the form of an expansible chamber having an open ended spring wound therearound, expansion of the spring indicating gas pressure.
U.S. Pat. No. 4,018,231 to Wallace of Apr. 19, 1971 discloses a pilot balloon which is pre-stretched in deflated condition with spaced folds forming ridges and troughs to signal visually the non-inflated condition. The ridges expand radially to indicate inflation visually.